A high color rendering white light emitting diode (WLED) is generally produced by combining yellow and red mixed phosphors on a blue chip. Herein we report a single component phosphor...

Materials with near-infrared (NIR) persistent luminescence (PersL) and NIR-to-NIR photostimulated luminescence (PSL) properties are attractive platforms for photonic energy harvesting and release. In this work, we develop Mg 2 SnO 4 :Cr as a broadband NIR PersL and NIR-to-NIR PSL material (luminescence maxima at ∼800 nm) and reveal the origin of the PersL and PSL properties. The material has an inverse spinel structure with the Mg 2+ and Sn 4+ disorder at the Wyckoff 16d site based on the Rietveld refinement. Cr K-edge X-ray absorption near-edge structure (XANES) spectra uncover that the doped Cr ions have a +3 valence state and occupy the disordered (Mg,Sn) site with octahedral coordination. The disorder results in multiple Cr 3+ centers, and the broadband luminescence originates from the 4 T 2 ( 4 F) → 4 A 2 transition of Cr 3+ at sites with intermediate crystal field strength. The distribution of trap depths is continuous according to the analysis of thermoluminescence (TL) spectra using the initial rising method, which relates to the random distribution of Mg 2+ and Sn 4+ at the second coordination sphere of the Cr 3+ centers rather than the oxygen-related defects. Stimulating the material with a NIR laser, the NIR PersL gets significantly enhanced due to a PSL process. The broadband PersL and PSL are detectable beyond 100 h and have good tissue penetrability and therefore the developed Mg 2 SnO 4 :Cr 3+ has potential in applications of optical information storage/reading and autofluorescence-free bioimaging. Finally, three crystal and electronic structure factors are proposed for screening new Cr 3+ -activated PersL and PSL materials.

Developing novel luminescent materials with ideal properties is an endless project, urged by growing requirements of advances in energy saving, healthy lighting and environmental friendliness. Herein, a series of ScCaOBO3:Ce3+,Mn2+...